Loop long-distance footpath follows the Turkey Brook to the north of Forty Hall. Nearby to the north in Bulls Cross are Myddelton House Gardens (former home of botanist E. A. Bowles, open at certain times during the year) and Capel Manor horticultural college with of grounds open to the public, including a maze and themed gardens. Special events take place here throughout the year. Also nearby are Whitewebbs Park and Clay Hill House. Geology (and formation of the hill) Sources for the material in this section include those listed in "Notes and References", below. The hill which gives its name to the district lies to the north of the built-up area and is mainly occupied by Forty Hall and its grounds. It rises to a small plateau around 50 metres (160 ft) above sea level. This plateau is capped by Boyn Hill Gravel, a deposit laid down by the River Lea during cold climate conditions approximately 400,000 years ago, when that river lay further to the west, and at a higher altitude, than it does today. At Boyn Hill time, the area where Forty Hill is today was actually in the bottom of the valley of the southward-flowing River Lea. The Boyn Hill gravel was deposited there, along a line linking Bulls Cross to Forty Hill, Bush Hill, Palmers Green and beyond, to the River Thames. Also at Boyn Hill time, two of the Lea's tributaries, Cuffley Brook and Turkey Brook, flowed from higher ground to the north-west. They cut through pre-glacial sand and gravel and glacial till (the latter having been deposited by the Anglian ice advance about 450,000 years ago). These tributaries joined the Lea at points not far away from each other, north and south of where Forty Hall is today, at what is now an altitude of c50m. Then the River Lea moved steadily towards the east. And, as a contour map shows, the two brooks each extended eastwards with the Lea, but stayed apart. The Lea and the two brooks cut down into the London Clay (to a today's altitude of c35m), thus defining the north, east and south sides of what was becoming Forty Hill. (Forty Hill is thus an example of inverted relief, albeit on a small scale. Inversion of relief occurs "when materials on valley floors are, or become, more resistant to erosion than the adjacent valley slopes. As erosion proceeds, the